Safe and effective drug therapy by injection depends not only upon accurate diagnosis, but also on efficient and reliable introduction of the medical substance into the subcutaneous cellular tissue without introducing contaminants or ambient air. The applicable drug or pharmaceutical must first be drawn from the resident container or vial into a syringe before injection. The integrity and features of the vial, therefore, are influential over the overall safety of the injection.
Problems associated with injections are complicated when the medication to be administered must be stored as two separate component parts, then mixed, prior to injection. Dual chamber vials have been developed to facilitate storage and mixing of these two-component medications. Common examples of multipart medications include medications which must be mixed from a component A, usually a preservative or catalyst, and a component B, which is usually a pharmaceutical. Component A or component B may be in powder or crystalline form instead of liquid form.
Dual chamber vials have been developed which allow an A component and a B component to remain separated in independent chambers within a single package until mixing is desired. The vial allows mixing of the component parts in that same unitary package. In an example of such a device is the MIX-O-VIAL two compartment vial manufactured by the Upjohn Company of Kalamazoo, Mich. This device is a single vial container having two chambers separated by a small stopper. The septum is formed by a stopper-piston slidably mounted within the vial at one end. The stopper-piston is forced into the vial to pressurize the chamber between the stopper-piston and the plug doing so displaces a plug lodged in a small orifice separating the two chambers. The displaced plug floats freely in the other chamber and is used as an agitator to mix the two component parts together. The two components are free to flow between chambers through the connecting orifice and thereby mix together. Although this device has proven quite useful, it has its disadvantages.
While in many cases having an over-pressure (as is produced in the MIX-O-VIAL) existing within a vial is not a problem, if the pharmaceuticals are in the form of cytotoxins used for chemotherapy, over-pressure within the vial could create safety problems. It is quite possible that upon accessing the vial, a quantity of the cytotoxin could be accidentally released onto the skin of a health care worker. Cytotoxins are quite dangerous in this concentrated form and are capable of destroying tissue they come in contact with.
Pharmaceutical components are sometimes sensitive to how violently they are mixed. For example, certain lyophilized crystals of human growth hormone, when mixed with a liquid carrier, must be mixed slowly. Mixing too quickly can cause damage to the pharmaceutical. The mechanical crushing, shearing and tearing which can accompany rapid mixing caused by a loose solid agitator, can break up the molecules into subcomponents which do not retain the same medical qualities.